Improved electrical actuation and dielectric strength of rubber composites with polydopamine noncovalent and silane covalent modification of carbon nanotube

A dielectric elastomer actuator (DEA) is regarded as an intelligent actuator that can reproduce the performance of human muscle. A core-shell structured dielectric filler is synthesized by modifying carbon nanotube (CNT) with polydopamine (PDA) noncovalently and 3-mercaptopropyl ethyoxyldi (tridecyl-pentaethoxy) silane (Si747) covalently, designated as PDASi747@CNT. Then, the filler is incorporated into an epoxy natural rubber (ENR) matrix to yield dielectric elastomer composites, denoted as PDA-Si747@CNT/ENR. The PDA and Si747 modifications improve not only the filler dispersion but also the dielectric strength of the ENR composites. More importantly, Si747 is involved in vulcanization and provides chemical bonds between CNT and ENR chains. The maximum actuated strain of the PDA-Si747@CNT/ENR composites increases to 17.9% at 55.5 kV mm(-1), which is 152% higher than that of CNT/ENR composites (7.1% at 30 kV mm(-1)). Furthermore, the ENR composite-based DEA demonstrates excellent stability and reliability, which is advantageous for practical applications. (c) 2023 Society of Industrial Chemistry.